A turbo chiller including a turbo heat pump can store a larger amount of refrigerant than other chillers and heat pumps, and a turbo chiller having, for example, a capacity at the level of 500 refrigeration ton can store about 700 to 800 kg of refrigerant. Refrigerants used for turbo chillers at present are HFC134a, HFC245fa, and the like that are considered not to harm the ozone layer, but these refrigerants all have a high global warming potential (GWP) and are considered to have a significant influence on global warming.
Further, such a turbo chiller is installed in a machine room of a building in many cases. If refrigerant leakage should occur due to an accident or the like, the refrigerant, which is heavier than air, pools in a lower portion. Unfortunately, the refrigerant leakage can be detected only at the time at which the refrigerant has leaked up to a concentration at which the refrigerant can be detected by a refrigerant detection sensor set in the machine room or at the time at which the chiller trips after discharge of the entire refrigerant. In both cases, a large amount of refrigerant leaks to be emitted into the atmosphere.
Meanwhile, in other air conditioners, chillers, heat pumps, and the like, a large number of refrigerant leakage detection sensors are set below a compressor, a condenser, an evaporator, and the like constituting a refrigeration cycle or to valves, joints, and the like provided to refrigerant pipes and connection portions of various components. When refrigerant leakage is detected by each refrigerant leakage detection sensor, an alarm is issued, and the occurrence site of the refrigerant leakage can be identified. PTLs 1 to 3 and the like present such an air conditioner or chiller or the refrigerant leakage detection sensor applied thereto.